Erhaia is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of small to minute freshwater snail

Freshwater snail

A freshwater snail is one kind of freshwater mollusc, the other kind being freshwater clams and mussels, i.e. freshwater bivalves. Specifically a freshwater snail is a gastropod that lives in a watery non-marine habitat. The majority of freshwater gastropods have a shell, with very few exceptions....

s with a gill

Gill

A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

 and an operculum

Operculum (gastropod)

The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...

, aquatic

Aquatic animal

An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...

 gastropod mollusks in the family Amnicolidae

Amnicolidae

Amnicolidae is a family of small freshwater snails with a gill and an operculum, aquatic gastropod mollusks.This family is in the superfamily Rissooidea and in the clade Littorinimorpha...

.

Erhaia is the type genus

Type genus

In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...

 of the tribe Erhaiini, which is now a synonym of the subfamily Amnicolinae.

Erhaia (also within the tribe Erhaiini) was originally described as a genus within the Pomatiopsidae

Pomatiopsidae

Pomatiopsidae is a family of small mainly freshwater snails with gills and an operculum, aquatic gastropod mollusks in the superfamily Rissooidea ....

 in 1985, but Wilke et al. (2000, 2001) moved it to the Amnicolidae.

Distribution

The distribution of Erhaia includes southern China and India. The center of biodiversity of Erhaia in China is located in the provinces of Hunan

Hunan

' is a province of South-Central China, located to the south of the middle reaches of the Yangtze River and south of Lake Dongting...

, Hubei

Hubei

' Hupeh) is a province in Central China. The name of the province means "north of the lake", referring to its position north of Lake Dongting...

 and Sichuan

Sichuan

' , known formerly in the West by its postal map spellings of Szechwan or Szechuan is a province in Southwest China with its capital in Chengdu...

. Distribution also includes Fujian Province. There is also scattered occurrences of Erhaia in Yunnan

Yunnan

Yunnan is a province of the People's Republic of China, located in the far southwest of the country spanning approximately and with a population of 45.7 million . The capital of the province is Kunming. The province borders Burma, Laos, and Vietnam.Yunnan is situated in a mountainous area, with...

 Province. These snails live in the Yangtze River

Yangtze River

The Yangtze, Yangzi or Cháng Jiāng is the longest river in Asia, and the third-longest in the world. It flows for from the glaciers on the Tibetan Plateau in Qinghai eastward across southwest, central and eastern China before emptying into the East China Sea at Shanghai. It is also one of the...

 drainage and in the Mekong River drainage (1 species).

Species

Species within the genus Erhaia include:

• Erhaia daliensis Davis & Kuo, 1985
• Erhaia gongjianguoi (Kang, 1983)
• Erhaia hubiensis (Liu, Zhang & Wang, 1983)
• Erhaia jianouensis (Liu & Zhang, 1979)
• Erhaia kunmingensis Davis & Kuo, 1985
• Erhaia lii (Kang)
• Erhaia nainitalensis Davis & Rao, 1997
• Erhaia robusta (Kang, 1986)
• Erhaia sheminensis
• Erhaia wantanensis
• Erhaia wufengensis

Synonyms:

• Erhaia chinensis Davis et al. 1985 and Erhaia chinensis Davis & Kang, 1995 are synonyms of Chencuia chinensis Liu & Zhang, 1979